Finding the Fourth Proportional to 1,131.76, 1,561.48 and 689.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,131.76 : 1,561.48 = 689.55 : x
2. Step 2: Convert to fraction form
   1,131.76/1,561.48 = 689.55/x
3. Step 3: Cross multiply
   1,131.76x = 1,561.48 × 689.55
4. Step 4: Simplify right side
   1,131.76x = 1,076,718.53
5. Step 5: Solve for x
   x = 1,076,718.53/1,131.76
6. Step 6: Final answer
   x = 951.37